The embodiments described herein relate generally to wind turbines, and more particularly, to methods and systems for improving efficiency of a wind turbine rotor.
Some wind turbines may include a cast iron hub coupled to a shaft of a wind turbine, wherein the blades are coupled to the hub. More particularly, conventional wind turbine rotors may use a three-bladed configuration wherein root ends of the blades are coupled to the hub. These root ends, however, may not be aerodynamically shaped and may not produce power from the wind. More particularly, a portion of the blade near the root end may not produce any appreciable aerodynamic lift.
In order to reach higher energy conversion, the aerodynamic efficiency of the wind turbine may be improved by increasing the blade size of the wind turbine. Increasing the blade size, however, usually involves increasing the size of other components and machinery of the wind turbine which may lead to higher wind turbine costs. More particularly, transportation costs, fabrication costs and/or installation costs can increase for larger sized blades. Moreover, increasing the blade size may result in a higher load on a pitch assembly and a yaw assembly, and in particular, the respective bearings of these assemblies due to bending moments and/or thrust forces created by large rotor blades. More particularly, bending moments and/or thrust forces can override the charging limit of typical bearings.
Moreover, due to the aerodynamic loads experienced during operations, larger blades may experience flap and in-plane bending moments at the root ends which may reduce efficiency of the wind turbine. Aerodynamic loads may cause deflection at the tip ends of large blades, wherein excessive tip deflection can be catastrophic if the blades contact the wind turbine tower.